Customer.io - We make it easy to send emails triggered by user behavior. Build, measure and improve your emails to activate and retain users

Zendesk - Zendesk is a beautiful, lightweight help-desk solution.

HubSpot - Grow Better With HubSpot: Software that's powerful, not overpowering. Seamlessly connect your data, teams, and customers on one CRM platform that grows with your business.

Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community

If No Reply - Simple email automation that works for Gmail

HelpScout - Help Scout is a simple, straightforward way to provide excellent support